1. Field of the Invention
The present invention relates to a light emitting device and a method of driving the same. Particularly, the present invention relates to a light emitting device which can reduce consumption of an electric power in screen protecting mode and a method of driving the same.
2. Description of the Related Art
A light emitting device emits a light having a certain wavelength when a predetermined voltage is applied thereto.
FIG. 1 is a plan view illustrating pixel in a common organic electroluminescent device. FIG. 2 is a plan view illustrating a process of emitting a light in the pixel.
Referring to FIG. 1, the organic electroluminescent device includes a panel having a plurality of pixels 3.
At least one pixel includes an anode electrode layer 4, an organic layer 10, and a cathode electrode layer 12, disposed in sequence.
The organic layer 10 includes an electron injection layer 10A, an electrode transporting layer 10B, an emitting layer 10C, a hole transporting layer 10D and a hole injection layer 10E.
When certain voltages are applied to the anode electrode layer 4 and the cathode electrode layer 12, electrodes generated from the cathode electrode layer 12 are transported to the emitting layer 10C through the electron injection layer 10A and the electron transporting layer 10B. In addition, holes generated from the anode electrode layer 4 are transported to the emitting layer 10C through the hole injection layer 10E and the hole transporting layer 10D. Then, the electrodes and holes are recombined in the emitting layer 10C, and so a light is emitted from the emitting layer 10C.
The anode electrode layer 4 is made up of a transparent conductible substance such as indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO).
The hole injection layer 10E adjusts the concentration of the holes, and the hole transporting layer 10D controls the moving velocity of the holes. As a result, the holes generated from the anode electrode layer 4 are easily injected into the emitting layer 10C.
The electron injection layer 10A adjusts the concentration of the electrons, and the electron transporting layer 10B controls the moving velocity of the electrons. As a result, the electrons generated from the cathode electrode layer 12 are easily injected into the emitting layer 10C.
The organic electroluminescent device emits a light through the above process. On the other hand, in the organic electroluminescent device, in case that a same image is continuously displayed on a part of the panel, elements corresponding to the part are deteriorated more rapidly than ones corresponding to the other part. In detail, particular pixel is continuously turned on in accordance with first data signals in some area of the panel. However, certain pixel is continuously turned off in accordance with second data signals in some area of the pixel. Accordingly, the pixels have different deterioration velocity. In other words, in case that an image is continuously displayed on a part of the pixel, pixels which are turned on are deteriorated more rapidly than ones which are turned off. As a result, in the organic electroluminescent device, an image distortion phenomenon may be occurred on the screen of the panel which is used for a long period of time. Additionally, the consumption of electric power is high in the organic electroluminescent device.